Legacy communications systems such as the Personal Handy-phone System (PHS) are configured to be simple and low cost. Differential demodulation has been adopted based on the technological constraints present at the time of designing these systems for baseband demodulation and therefore does not have the capability to combat inter-symbol-interference.
It is therefore desirable to provide a modernized baseband design compatible with or to retrofit these legacy systems. It is further desirable to employ advanced DSP algorithms and introduce adaptive equalization to realize coherent demodulation. In such systems the use of delay buffers is required to allow calculation of frequency offset data or rotation angles for correction of the demodulated data. It is also desirable to improve the storage efficiency of these delay buffers to reduce size and power requirements.